Mother Akon Guode, who stands accused of murdering three of her children by driving into a lake, has broken down in the dock, wailing hysterically as a harrowing triple-zero call of their final moments was played.

The call to authorities was  made by Alexandra Colston-Ing,  a teacher who happened on the scene and described seeing a car with somebody in the front and "movement in the back" driven "full bolt," into a lake on the afternoon of April 8, 2015.

Akon Guode at the funeral of her three children iast year. Photo: Getty Images

Ms Colston-Ing initially sounds calm as she tells the operator she had just watched a car being "deliberately" driven into the Wyndham Vale lake and that she's driving back around to get  closer to the sinking car.

"I saw them deliberately drive in there, well it looked like that anyway," she tells an operator.

"They'd have to fully mount the kerb, drive along a grass area… I saw them just drive full bolt into the water."

Bol, 1, left, Anger, 4, centre and her twin brother Madit, right, were killed when their mother's car crashed into the lake.

Ms Guode, 36, has been accused of murdering her three youngest children - Bol, 16-months-old, four-year-old twins Hanger and Madit, and attempting to murder six-year-old Aluel, who was also in the car when it went into Lake Gladman but survived.

Ms Colston-Ing becomes increasingly hysterical as she tells the operator that there are "children in the water".

At that point in the recording, Ms Guode fell to the ground and her wails filled the courtroom until proceedings were halted.

The three children died after a car was driven into a lake in Wyndham Vale. Photo: Luis Ascui

Other members of the Sudanese community who were present in the courtroom also began to sob.

Ms Guode's lawyer Julian McMahon climbed into the dock with his client, kneeling down beside her and holding her hand as she continued to wail violently for more than ten minutes.

In the recording played in court, Ms Colston-Ing had said she was moving closer to the lake to get a better view of the car before her voice suddenly changes as she describes a horror scene before her.

"It's gone pretty deep...Its now up past the front windshield.  I'm just heading back around there now, bear with me a second I'm coming up to it now," she told the operator..

"(inaudible) in the car and they're screaming...

"They're floating, They're floating in the water, (inaudible) can't swim. I can help this kid, I can help them, please let me."

The operator repeatedly advises the woman to keep herself safe and wait for emergency services to arrive.

The court was closed for a short period of time after Ms Guode broke down.  When it resumed she was missing from the dock and Mr McMahon asked that she be excused for the rest of the day and also from Thursday's proceedings.

He said Ms Guode had sobbed uncontrollably for 15 minutes and then "shook as if she was freezing". 

"That is a traumatic episode," Mr McMahon said.

He said his client needed to sleep and put the police on notice that he would cross examine any medical staff who found her fit to appear in court on Thursday.

Prosecutor Michele Williams QC had said simply not wanting to hear the evidence was not sufficient grounds for Ms Guode to be absent from court. "She should hear what the evidence is against her, all of it," she said.

Earlier on Wednesday a teacher of Ms Guode's eldest surviving daughter Akoi Chabiet, 18, gave evidence, telling the court the teenager had told her that "mum shouldnt be driving," about four months before the incident.

Biology teacher Viveka Simpson told the court Ms Chabiet had said her mum had to pull over because she'd been "dizzy," had lost her vision and felt numb.

The evidence examined has has centred on Ms Guode's physical and mental health in the lead up the incident, as well as financial and social pressures that may have been weighing on the mother-of-seven, originally from South Sudan.

The father of the four children driven into the lake - Joseph Manyang - on Tuesday gave evidence that he and Ms Guode "loved each other" and the children and that she would never have intentionally hurt them.

He has continued to visit her in custody and said she'd told him she was "dizzy," which he'd taken to be an explanation for what happened at the lake, he said.

Magistrate Carolene Gwynn stood the hearing down until Thursday morning when she is expected to make a decision about whether Ms Guode must appear to hear the evidence of other first responder witnesses.